A fan made of metal or plastic is widely used to remove heat produced by electronic elements. When the blades of the fan are made of plastic by injection technology processing, each blade must have a certain thickness, normally thicker than 0.3 mm, since the fan is unlikely to add the number of blades to thereon, or it could break due to high instant stress of wind resistance when operating. Therefore, the inventor tries to develop a fan blade with improved structure to overcome the foregoing drawbacks in the prior art fan.